Proprioceptive Actuator Design in the MIT Cheetah: Impact Mitigation and High-Bandwidth Physical Interaction for Dynamic Legged Robots

Wensing, Patrick M.; Wang, Albert; Seok, Sangok; Otten, David; Lang, Jeffrey H.; Kim, Sangbae

doi:10.1109/tro.2016.2640183

Cited by 385 publications

(238 citation statements)

References 36 publications

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“…With low gear ratio, often between 5:1 and 25:1, proprioceptive actuation can be achieved [5], [25], [30]. Proprioceptive actuators do not require dedicated force sensors as joint torque is directly estimated from motor phase current measurement [35].…”

Section: Related Workmentioning

confidence: 99%

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An Open Torque-Controlled Modular Robot Architecture for Legged Locomotion Research

Grimminger

Meduri

Khadiv

et al. 2020

IEEE Robot. Autom. Lett.

173

117

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We present a new open-source torque-controlled legged robot system, with a low cost and low complexity actuator module at its core. It consists of a low-weight high torque brushless DC motor and a low gear ratio transmission suitable for impedance and force control. We also present a novel foot contact sensor suitable for legged locomotion with hard impacts. A 2.2 kg quadruped robot with a large range of motion is assembled from 8 identical actuator modules and 4 lower legs with foot contact sensors. To the best of our knowledge, it is the most lightest force-controlled quadruped robot. We leverage standard plastic 3D printing and off-theshelf parts, resulting in light-weight and inexpensive robots, allowing for rapid distribution and duplication within the research community. In order to quantify the capabilities of our design, we systematically measure the achieved impedance at the foot in static and dynamic scenarios. We measured up to 10.8 dimensionless leg stiffness without active damping, which is comparable to the leg stiffness of a running human. Finally, in order to demonstrate the capabilities of our quadruped robot, we propose a novel controller which combines feedforward contact forces computed from a kino-dynamic optimizer with impedance control of the robot center of mass and base orientation. The controller is capable of regulating complex motions which are robust to environmental uncertainty. *

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Section: Related Workmentioning

confidence: 99%

“…Only a few sensing principles remain functional at harsh impact conditions, like high-speed leg touchdowns. Peak forces can exceed two times bodyweight when exerted onto a single foot [35]. Light-weight force-sensing based on piezoresistive or optical sensing of deflecting elastic material has been demonstrated previously [19], [25].…”

Section: Related Workmentioning

confidence: 99%

An Open Torque-Controlled Modular Robot Architecture for Legged Locomotion Research

Grimminger

Meduri

Khadiv

et al. 2020

IEEE Robot. Autom. Lett.

173

117

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show abstract

“…The robot is designed to deliver 72 Nm torque to provide more than 50% of biological lower limb joints as our control philosophy is to use small to medium levels of torque in combination with optimized timing, magnitude, and profile of torque trajectories [3]. Quasi-direct drive actuation [28] [29] is a new paradigm of robot actuation design that leverages high torque density motors with low ratio transmission mechanism. In this paper, the quasi-direct drive is a generalized definition to describe actuation with low ratio transmission mechanism because of high torque density motors without necessarily referring to motors directly attached to mechanical loads as its conventional definition.…”

Section: Design Requirementsmentioning

confidence: 99%

“…In this paper, the quasi-direct drive is a generalized definition to describe actuation with low ratio transmission mechanism because of high torque density motors without necessarily referring to motors directly attached to mechanical loads as its conventional definition. It has been recently studied for legged robots [28] and exoskeletons [30]. To our knowledge, this paper is the first work to investigate quasi-direct drive and its feasibility for wearable knee co-robots to augment squatting movement.…”

Section: Design Requirementsmentioning

confidence: 99%

Design and Control of a High-Torque and Highly Backdrivable Hybrid Soft Exoskeleton for Knee Injury Prevention During Squatting

Huang

Wang

et al. 2019

IEEE Robot. Autom. Lett.

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This paper presents design and control innovations of wearable robots that tackle two barriers to widespread adoption of powered exoskeletons, namely restriction of human movement and versatile control of wearable co-robot systems. First, the proposed quasi-direct drive actuation comprising of our customized hightorque density motors and low ratio transmission mechanism significantly reduces the mass of the robot and produces high backdrivability. Second, we derive a biomechanics model-based control that generates biological torque profile for versatile control of both squat and stoop lifting assistance. The control algorithm detects lifting postures using compact inertial measurement unit (IMU) sensors to generate an assistive profile that is proportional to the biological torque produced from our model. Experimental results demonstrate that the robot exhibits low mechanical impedance (1.5 Nm resistive torque) when it is unpowered and 0.5 Nm resistive torque with zero-torque tracking control. Root mean square (RMS) error of torque tracking is less than 0.29 Nm (1.21% error of 24 Nm peak torque). Compared with squatting without the exoskeleton, the controller reduces 87.5%, 80% and 75% of the of three knee extensor muscles (average peak EMG of 3 healthy subjects) during squat with 50% of biological torque assistance.To overcome the limitations of restriction of natural movement and versatile control of human-robot interaction [2,26], the contributions of this work include: 1) a quasi-direct drive actuation paradigm using our high torque density motors

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“…Recent work on finding appropriate motors and reduction ratio can be found in [68] using the an upper and a lower bound on the inertia of the robot. The highest angular momentum take place at the level of the hip and the knee.…”

Section: Actuators With Electric DC Motorsmentioning

confidence: 99%

An Overview of Humanoid Robots Technologies

Stasse

Flayols

2018

Springer Tracts in Advanced Robotics

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Proprioceptive Actuator Design in the MIT Cheetah: Impact Mitigation and High-Bandwidth Physical Interaction for Dynamic Legged Robots

Cited by 385 publications

References 36 publications

An Open Torque-Controlled Modular Robot Architecture for Legged Locomotion Research

An Open Torque-Controlled Modular Robot Architecture for Legged Locomotion Research

Design and Control of a High-Torque and Highly Backdrivable Hybrid Soft Exoskeleton for Knee Injury Prevention During Squatting

An Overview of Humanoid Robots Technologies

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